A sedentary lifestyle is a type of lifestyle with no or irregular physical activity. A person who lives a sedentary lifestyle may colloquially be known as a couch potato. It is commonly found in both the developed and developing world. Sedentary activities include sitting, reading, socialising, watching television, playing video games, and computer use for much of the day with little or no vigorous physical exercise. A sedentary lifestyle can contribute to many preventable causes of death. Screen time is the amount of time a person spends watching a screen such as a television, computer monitor, or mobile device. Excessive screen time is linked to negative health consequences.[1][2][3][4]

Sitting still may cause premature death. The risk is higher among those that sit still more than 5 hours per day. It is shown to be a risk factor on its own independent of hard exercise and BMI. The more still, the higher risk of chronic diseases. People that sit still more than 4 hours per day have a 40 percent higher risk than those that sit fewer than 4 hours per day. However, those that exercise at least 4 hours per week are as healthy as those that sit fewer than 4 hours per day.[6][7]

A sedentary lifestyle and lack of physical activity can contribute to or be a risk factor for:

As a response to concerns over health and environmental issues, some organizations have promoted active travel, which seeks to promote walking and cycling as safe and attractive alternatives to motorized transport.[21] Additionally, some organizations have implemented exercise classes at lunch, walking challenges among co-workers, or allowing employees to stand rather than sit at their desk during the workday. Workplace interventions such as alternative activity workstations, sit-stand desks, promotion of stair use are among measures being implemented to counter the harms of sedentary workplace environments.[22] A Cochrane systematic review published in 2016 concluded that "at present there is very low quality evidence that sit-stand desks can reduce sitting at work at the short term. There is no evidence for other types of interventions." Also, evidence was lacking on the long term health benefits of such interventions.[23] Organizations may also offer cholesterol or blood pressure screenings to employees.[citation needed]

The term couch potato was coined by a friend of underground comics artist Robert Armstrong in the 1970s; Armstrong featured a group of couch potatoes in a series of comics featuring sedentary characters and with Jack Mingo and Allan Dodge created a satirical organization that purported to watch television as a form of meditation. With two books and endless promotion through the 1980s, the Couch Potatoes appeared in hundreds of newspapers, magazines and broadcasts, spreading its "turn on, tune in, veg out" message, garnering 7,000 members, and popularizing the term.

The condition, which predates the term, is characterized by sitting or remaining inactive for most of the day with little or no exercise.

Lack of exercise causes muscle atrophy, i.e. shrinking and weakening of the muscles and accordingly increases susceptibility to physical injury. Additionally, physical fitness is correlated with immune system function;[24] a reduction in physical fitness is generally accompanied by a weakening of the immune system. A review in Nature Reviews Cardiology suggests that since illness or injury are associated with prolonged periods of enforced rest, such sedentariness has physiologically become linked to life-preserving metabolic and stress related responses such as inflammation that aid recovery during illness and injury but which due to being nonadaptive during health now lead to chronic diseases.[25]

Despite the well-known benefits of physical activity, many adults and many children lead a relatively sedentary lifestyle[26][27] and are not active enough to achieve these health benefits.

In the 2008 United States American National Health Interview Survey (NHIS) 36% of adults were considered inactive. 59% of adult respondents never participated in vigorous physical activity lasting more than 10 minutes per week.[28]

^Olds, T.; Ridley, K.; Dollman, J. (2006). "Screenieboppers and extreme screenies: The place of screen time in the time budgets of 10–13 year-old Australian children". Australian and New Zealand Journal of Public Health. 30 (2): 137–142. doi:10.1111/j.1467-842X.2006.tb00106.x. PMID16681334.